“Waters of the U.S.” in Montana Farmland

Maps by GeosyntecAnalysis by American Farm Bureau Federation

Area of focus is near Denton, Montana in Fergus County.

Large, 100-year flooplains, shown in hash marks, are common throughout the state.

Previous rules/guidance – Tributaries and Adjacent Wetlands

Absent case-specific “significant nexus” finding, only perennial and intermittent tributaries (blue lines) and adjacent wetlands (green shapes) deemed jurisdictional.

(Note: light blue shapes designate freshwater ponds.)

New WOTUS Rule – More Automatically Regulated “Tributaries”

Ephemeral tributaries (red lines) deemed jurisdictional without further analysis. Ditches also regulated if “excavated in” or “relocated” a tributary.

Note: This map does not show jurisdictional ditches and may not include all ephemeral tributaries.

New WOTUS Rule – Automatically Regulated Adjacent Waters

Includes all “waters”—including wetlands—that lie even partially within a 100-foot buffer (pink shading) around all perennial, intermittent and ephemeral streams.

New WOTUS Rule – More Automatically Regulated Adjacent Waters

Includes all “waters”—including wetlands—where any part is within the 100-year floodplain and not more than 1,500 feet from a tributary. Light green shading shows the 1,500-feet zone and hash marks show the known FEMA Flood

Zone maps (which may be out-of-date or may not be relied upon by the Corps).

In this area, given the wide 100-year flood zone, any water even partially within the light green shading is an “adjacent water.”

New WOTUS Rule – Maybe Regulated “Significant Nexus” Waters

Water/wetlands even partially within 4,000 feet (about ¾ mile) of a tributary can be regulated on a “significant nexus” finding. Orange shading shows land outside the adjacency zone but within the 4,000 feet zone.

Even without mapping around jurisdictional ditches, the area of possible regulation covers the entire map.

State-Wide “Waters of the U.S.” Zones

 

Montana Acres Share of Total Acres

Total Acres in State 94,234,434

Acres w/i 100-ft buffer (adjacent) 9,523,961 10%

Acres w/i 1,500-ft buffer (possibly adjacent) 81,038,377 86%

Acres w/i 4,000-ft buffer (subject to “significant nexus” finding)

92,931,227 99%